274 



VERTEBRATE SKELETON 



Hipposiderinae, extends to the ilium, enclosing a preacetabular foramen. The 

 acetabulum is high on the pelvis and is directed more or less upwards. 



Edentata. — The pelvis is short in sloths, longer in other Xenarthra, and 

 longest in Tubulidentata. The ilia are broadest in sloths; in other forms they 

 are broad above and narrower near the acetabulum. Except in Tubulidentata, 

 the ischia are fused with several (five in armadillos) synsacrals, bounding a 

 sacro-ischiadic fenestra. The symphysis is short (of the pubes only in Oryctero- 

 pus) and is usually ossified. The obturator fenestra is large. 



RODENTIA have the ilium short and slender, pubes and ischia flat, the pelvic 

 bones diverging behind. The long symphysis is often ossified, an exception 

 occurring in guinea pigs where the halves are connected by ligament. 



Carnivora. — The pelves of the Fissipedia and Pinnipedia differ consider- 

 ably. The former have a long and narrow pelvis, the subequal ilium and ischium 

 being in a straight line. The ilium is usually straight 

 and flat, narrower near the acetabulum, and expanded as 

 a crest dorsal to the sacral articulation. The long sym- 

 physis includes ischium and pubis and the obturator 

 fenestra is oval. The Pinnipedia have very short ilia, the 

 crests turned outwards; pubes and ischia are long and 

 slender, the fenestra long and narrow. The symphysis is 

 short, the halves slightly connected. The acetabulum 

 lacks the incisure for the teres ligament. 



Fig. 299. — Ventral 

 view of pelvis of Scap- 

 anus latim&nus, showing 

 absence of symphysis. 



Fig. 300. — Pelvis of Pteropus. a, acetabulum; //, ilium; is, 

 ischium; p, pubis. 



Cetacea have a long, slender bone (?ischium) on either side of the body, 

 this longer in the male. It is nearly parallel with the backbone and is connected 

 with its fellow by ligament. Balcena has a rudimentary acetabulum and rem- 

 nants of a femur. Plaianista has lost the pelvis entirely. 



UNGUL.A.TA have a long pelvis, the iHum expanded dorsally, narrower near 

 the acetabulum, the dorsal crest turned outwards in Artiodactyls. Ruminants 

 have a large preacetabular fossa. The symphysis is long in Artiodactyls, includ- 

 ing most of the ischium, the fenestra being oval. The ischium is shorter, the 

 fenestra nearly circular in Perissodactyls. 



Hyracoids recall the Artiodactyls in the appearance of the small pelvis. 



Proboscidia have a greatly expanded pelvis, the broad ilium being turned 

 outwards, the acetabulum looking downwards. Pubis and ischium are small, 

 both entering the symphysis, most of the ischium being included. 



